It is known that the performance of refractive optical elements may be improved or modified by the addition of micro- or nanostructures to one or more surfaces. For example, the quality of an inexpensive molded plastic or glass lens can be improved by the addition of a diffractive or binary optical layer that can correct aberrations, provide diffusion, beam shaping, beam-splitting or diffractive capabilities, or other wavefront corrections or modifications. In addition, biomimetic 3D patterns, such as motheye antireflection structures, can be formed on lenses to reduce surface reflections and glint.
Various well-known methods have been developed over the years to form micro- and nanoscale features on flat surfaces, including photolithography, molding, direct writing, nanoimprinting, etc., but these approaches are generally not readily applicable to curves surfaces, in particular to concave, convex and aspheric lenses. Techniques that are used, such as, for example, laser interferometry, are time consuming, expensive, and limited to periodic patterns that can be formed by interferometry. Once the pattern is formed (typically in photoresist), subsequent chemical or plasma etching, followed by liftoff, are required to transfer the pattern into the lens surface. These and other approaches do not lend themselves to high volume, low cost production, nor are they flexible in terms of their ability to rapidly change patterns or lens sizes and/or curvatures.
Thus there is a need for methods and systems by which the above shortcomings and limitations of the prior art of forming patterns on curved surfaces can be remedied.